Commit 4038866d authored by Venkateswararao Jujjuri (JV)'s avatar Venkateswararao Jujjuri (JV) Committed by Eric Van Hensbergen
Browse files

[net/9p] Add gup/zero_copy support to VirtIO transport layer.



Modify p9_virtio_request() and req_done() functions to support
additional payload sent down to the transport layer through
tc->pubuf and tc->pkbuf.
Signed-off-by: default avatarVenkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 9bb6c10a
......@@ -12,6 +12,9 @@
*
*/
/* TRUE if it is user context */
#define P9_IS_USER_CONTEXT (!segment_eq(get_fs(), KERNEL_DS))
/**
* struct trans_rpage_info - To store mapped page information in PDU.
* @rp_alloc:Set if this structure is allocd, not a reuse unused space in pdu.
......
......@@ -45,6 +45,7 @@
#include <linux/scatterlist.h>
#include <linux/virtio.h>
#include <linux/virtio_9p.h>
#include "trans_common.h"
#define VIRTQUEUE_NUM 128
......@@ -155,6 +156,14 @@ static void req_done(struct virtqueue *vq)
rc->tag);
req = p9_tag_lookup(chan->client, rc->tag);
req->status = REQ_STATUS_RCVD;
if (req->tc->private) {
struct trans_rpage_info *rp = req->tc->private;
/*Release pages */
p9_release_req_pages(rp);
if (rp->rp_alloc)
kfree(rp);
req->tc->private = NULL;
}
p9_client_cb(chan->client, req);
} else {
spin_unlock_irqrestore(&chan->lock, flags);
......@@ -202,6 +211,38 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
return 1;
}
/**
* pack_sg_list_p - Just like pack_sg_list. Instead of taking a buffer,
* this takes a list of pages.
* @sg: scatter/gather list to pack into
* @start: which segment of the sg_list to start at
* @pdata_off: Offset into the first page
* @**pdata: a list of pages to add into sg.
* @count: amount of data to pack into the scatter/gather list
*/
static int
pack_sg_list_p(struct scatterlist *sg, int start, int limit, size_t pdata_off,
struct page **pdata, int count)
{
int s;
int i = 0;
int index = start;
if (pdata_off) {
s = min((int)(PAGE_SIZE - pdata_off), count);
sg_set_page(&sg[index++], pdata[i++], s, pdata_off);
count -= s;
}
while (count) {
BUG_ON(index > limit);
s = min((int)PAGE_SIZE, count);
sg_set_page(&sg[index++], pdata[i++], s, 0);
count -= s;
}
return index-start;
}
/**
* p9_virtio_request - issue a request
* @client: client instance issuing the request
......@@ -212,22 +253,97 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
static int
p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
{
int in, out;
int in, out, inp, outp;
struct virtio_chan *chan = client->trans;
char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
unsigned long flags;
int err;
size_t pdata_off = 0;
struct trans_rpage_info *rpinfo = NULL;
int err, pdata_len = 0;
P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
req_retry:
req->status = REQ_STATUS_SENT;
if (req->tc->pbuf_size && (req->tc->pubuf && P9_IS_USER_CONTEXT)) {
int nr_pages = p9_nr_pages(req);
int rpinfo_size = sizeof(struct trans_rpage_info) +
sizeof(struct page *) * nr_pages;
if (rpinfo_size <= (req->tc->capacity - req->tc->size)) {
/* We can use sdata */
req->tc->private = req->tc->sdata + req->tc->size;
rpinfo = (struct trans_rpage_info *)req->tc->private;
rpinfo->rp_alloc = 0;
} else {
req->tc->private = kmalloc(rpinfo_size, GFP_NOFS);
if (!req->tc->private) {
P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: "
"private kmalloc returned NULL");
return -ENOMEM;
}
rpinfo = (struct trans_rpage_info *)req->tc->private;
rpinfo->rp_alloc = 1;
}
err = p9_payload_gup(req, &pdata_off, &pdata_len, nr_pages,
req->tc->id == P9_TREAD ? 1 : 0);
if (err < 0) {
if (rpinfo->rp_alloc)
kfree(rpinfo);
return err;
}
}
spin_lock_irqsave(&chan->lock, flags);
/* Handle out VirtIO ring buffers */
out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
req->tc->size);
in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
client->msize);
req->tc->size);
if (req->tc->pbuf_size && (req->tc->id == P9_TWRITE)) {
/* We have additional write payload buffer to take care */
if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
outp = pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
pdata_off, rpinfo->rp_data, pdata_len);
} else {
char *pbuf = req->tc->pubuf ? req->tc->pubuf :
req->tc->pkbuf;
outp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, pbuf,
req->tc->pbuf_size);
}
out += outp;
}
/* Handle in VirtIO ring buffers */
if (req->tc->pbuf_size &&
((req->tc->id == P9_TREAD) || (req->tc->id == P9_TREADDIR))) {
/*
* Take care of additional Read payload.
* 11 is the read/write header = PDU Header(7) + IO Size (4).
* Arrange in such a way that server places header in the
* alloced memory and payload onto the user buffer.
*/
inp = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata, 11);
/*
* Running executables in the filesystem may result in
* a read request with kernel buffer as opposed to user buffer.
*/
if (req->tc->pubuf && P9_IS_USER_CONTEXT) {
in = pack_sg_list_p(chan->sg, out+inp, VIRTQUEUE_NUM,
pdata_off, rpinfo->rp_data, pdata_len);
} else {
char *pbuf = req->tc->pubuf ? req->tc->pubuf :
req->tc->pkbuf;
in = pack_sg_list(chan->sg, out+inp, VIRTQUEUE_NUM,
pbuf, req->tc->pbuf_size);
}
in += inp;
} else {
in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM, rdata,
client->msize);
}
err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
if (err < 0) {
......@@ -246,6 +362,8 @@ req_retry:
P9_DPRINTK(P9_DEBUG_TRANS,
"9p debug: "
"virtio rpc add_buf returned failure");
if (rpinfo && rpinfo->rp_alloc)
kfree(rpinfo);
return -EIO;
}
}
......
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